The Research, Design And Implementation Of P2P VoD Model And The Simulator

At present, P2P live streaming system tends to practical use, but video-on-demand streaming system is still in its infancy. This thesis analyzes several typical models for P2P streaming media deeply. Aim at their deficiencies, and combined with their merits of the mesh structured system that is simple in protocol specification, strong in robustness, small control overhead due to the tree structure and easy in data scheduling, the thesis has designed a skip table based Video on Demand System ST-P2PVoD and its simulator PD-P2PSim. The simulation results show that the new model accelerates the speed to locate resource position and improves system performance when VoD VCR is operated. This thesis has discussed in depth to the key issues, such as the topology of ST-P2PVoD model, the node management, the data scheduling, the control protocols and interaction, and the design and implemention of the simulator PD-P2PSim.The ST-P2PVoD system model uses double layer topology that is based on skip tables and mesh structured partner nodes. Resource locating based on skip tables can effectively support the VCR operation, reduce VCR latency and server burden. The combined pull-push ideas are used to schedule data. According to the dynamic state of the VoD buffer, the push or pull way is selected to schedule data that ensures the data arrive as earlier as possible before playing, so as to enhance the effectiveness of the data scheduling and reduce control overhead. The types and formats of messages that are interacted between nodes in control protocol are defined. The message transmitting procedure among nodes and the message processing in nodes are also described in the thesis.This thesis has made research, design and implementation to the P2P network simulator PD-P2PSim. When designing this simulator, the commonality is taken into account; the object-oriented idea is used to design throughout overall structures. In order to raise the simulation speed when simulating a large-scale P2P nodes, compared to serially prossessing that is too slow by single-threaded discrete event driven model, this thesis designs "producers and consumers" double-threaded parallel discrete event driven model. On the basis of PD-P2PSim, the ST-P2PVoD system simulation model is implemented and tested, and is compared to the traditional P2VoD model in performance. The test results show that the new model has good scalability, robustness and efficiency.